I have noticed on my LS Teg with the rear ITR bar(Beaks kit) that although the understeer has been greatly reduced, it is still more than I like. If the gas tank is full it steers even more neutral. Given that the ITR has a larger diameter front bar, which would induce more understeer, what would be the next step to reduce understeer? I have played with the tire pressures (less in rear to reduce understeer) but am looking for a more hardware related answer.

 

more pressure in the rear will *decrease* understeer.

also go w/ higher rate springs and shocks in the rear.

 

Well my Yokohama tire guide tells me to reduce rear tire pressure to reduce understeer, or increase front pressure. I'm pretty sure that's how it works as I've been doing it for 10 years

 

Increase front camber and INCREASE (not decrease) rear tire pressures if anything.

What tire pressures are you running now? What tires?

Slow-in/fast out technique will reduce understeer too. You might be carrying too much speed into the corners.

 

OK now we can have a good debate

Why would Yokohama give these guidelines, which appear to be the opposite of what you have been doing? They say to reduce front camber(toward negative) and Reduce rear pressure(or increase front) to reduce understeer.

On my RX7 I followed those recommendations and noted a significant reduction in the understeer. Would a front driver be different?

The slow in fast out does work too, but I'm looking for equipment changes rather than driving style...

 

more pressure in the rear will cause more oversteer because it reduces the contact patch on the rear tires letting them slide easier causing oversteer. I did this for autox and it seemed to help with the sharp curves.

 

My opinion would be to increase pressure in the rear tires and more negative camber in the front. (this is for a front wheel drive car).. I've never owned a rear wheel drive car but it seems that if you would decrease the rears it would reduce understeer because would grip more and push towards the direction your front tires are pointing. Versus a FF car you would want your front tires to grip more than the rears. Just my opinion. This is the way I think hehehh.. Hope this helps.. sorry if i'm confusing..

tj

 

you can induce oversteer by decreasing the pressure in the rear tires; deflating the rear tires will cause them roll over easier and lose their contact patch. this will probably cause the tires to wear prematurely; the better way to increase oversteer is to add pressure to the rear.

 

You didn't tell us what kind of spring/shock combo your running. Generally, if you want a go-kart like quick spurts, you want softer suspension up front and firmer for the rear (in FWD cars). This will ensure that you're always mainting tire patch contact (w/ softer suspension w/ respect to the rears) and firmer rears will just glide along (hopefully losing contact and causing desired "oversteer".) Play with your spring/shock combo. Also, you could swap the front ITR sway w/ GS-R sway... having stiff suspension isn't always good for corners.

 

Sorry increase -ve front camber. When I refer to camber and increasing it, it's usually in the negative direction. I'm not sure why you would ever want to have +ve camber.

Yokohama's reasoning is correct, but I suppose interpretation debateable. For track/road course - to decrease understeer it makes sense to adjust the front tire pressures according to the load that tire will undergo and your predicted increase in tire pressure as tire temperature increases. You wouldn't want to increase front pressure too much because the tire has an ideal pressure that maximizes grip, and if you go beyond this pressure (say by overheating) your grip would start to decrease or the tread will start to disintegrate.

I typically see increases of 10 psi or more from cold to hot states when at the track. Ideally I try to keep the front pressures 30-32 psi (hot) with my tires. Any lower and the sidewalls start to flex too much; and higher and I lose traction.

To get oversteer in a FF car by changing only tire pressures, you want to increase the rear tire pressure so that the rear tires lose grip earlier than the fronts. This is a pretty broad generalization, mind you, but it does work up to a point. The only reason you want oversteer is so that you can get the car turned around so you can get on the gas faster after the apex. You can get on the gas sooner with a FF car (especially with an oversteering FF car) than a rear-drive car - because your power is going through the front wheels not the rears. Getting on the gas too early in a rear drive car often causes further rotation of the car (oversteer) and can make you spin. That's why the FF layout is easier to drive at the track IMHO.

 

I'm running Tokico Illuminas and springs, currently set at full soft for the street. Tires are AVS Intermediates, 195/50-15, pressures 34f, 32r. Stock LS front bar with ITR rear bar. I'm not looking for real point and shoot steering, but something that is better than I have now. It does steer almost like a rear driver, and I'd like it to be even closer

 

Try changing (increasing) the rebound/compression of your dampers (if adjustable). Why are you running them on their softest setting??

Changing tires might make a difference too.

Also, what is the weight of your car? Any extras in there? Stereo? Sub box?


[Modified by Big Phat R, 3:16 PM 8/24/2001]

 

You also can increase oversteer by setting the camber to 0 in the rear.Negative rear camber will slightly help create understeer.Also playing with suspension settings and spring rates will get you what you want.I have specially valved advanced design dampers with 10k front springs and 12k rear.That combined with zero camber in the rear the car turns in as much if not more than I would like.I can NOT get the car to push.I still have stock sway bars and no upper strut tower brace in the rear.

 

fastbrakes - definitely play w/ your shock settings. I would go 2 front and 3 in the back to start out. (Tokico's shocks are typically softer than Koni's... relatively speaking.) Also, why are you running 195/50/15's? Are you trying to change the gear ratio? In my experience, 195/50/15's (p-zero) have super short wall and, therefore, are pretty stiff. I would even out the pressure (34f/34r) and play around with it. All in all, play w/ your tires first, then the shocks, then both. Should take you a good month to sort things out (unless you've got an autoX coming up. )

 

what is the ride height of the car? a drop of 1.5" is more than enough. Also, as mentioned, stiffening dampening rate of rear in comparison to front will help.